Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<bits/stdc++.h>

#define mx 105
#define md 1000000007

using namespace std;

char c[mx][mx];
int w, h, dx[] = {0, 0, 1, -1}, dy[] = {1, -1, 0, 0}, ans;
struct P{int x, y, cs;};
queue<P> qu;
bool used[1005][1005] = {};

int main(){
  scanf("%d%d", &h, &w);
  for(int i = 0; i < h; i++){
    scanf("%s", c[i]);
    for(int j = 0; j < w; j++) {
      if(c[i][j] == '.') ans++;
    }
  }
  P goal = {h-1, w-1, 0};
  qu.push((P){0, 0, 1});
  used[0][0] = true;
  while(!qu.empty()){
    auto tmp = qu.front(); qu.pop();
    if(tmp.x == goal.x && tmp.y == goal.y){
      printf("%d\n", ans - tmp.cs);
      return 0;
    }
    for(int i = 0; i < 4; i++) {
      int x = tmp.x + dx[i], y = tmp.y + dy[i];
      if(0 <= x && x < h && 0 <= y && y < w && c[x][y] != '#' && !used[x][y]){
        used[x][y] = true;
        qu.push((P){x, y, tmp.cs + 1});
      }
    }
  }
  puts("-1");
}